Feasibility and outcome of partial open surgical fenestrated stent graft explantation, radical debridement, and in situ reconstruction for late graft infection

Aortic stent graft infection is a rare, but potentially lethal, complication of endovascular aortic aneurysm repair. Definitive treatment is complete stent graft explanation with in-line or extra-anatomical reconstruction. However, several factors can render such an operation unsafe, including the patient's overall fitness for surgery and partial incorporation of graft with a resulting robust inflammatory process, especially around the visceral vessels. We present the case of a 74-year-old man with a history of an infected fenestrated stent graft that was managed with partial explantation, wide debridement, and in situ reconstruction using a rifampin-soaked graft and a 360° omental wrap with good results.

The use of fenestrated and branched endografts for repair of complex aortic aneurysms continues to gain worldwide acceptance owing to the technique's minimally invasive nature and shorter convalescence compared with open surgical repair. [1][2][3] One of the most feared complications of endovascular abdominal aneurysm repair and thoracic aortic aneurysm repair is stent graft infection, occurring at a rate of 0.2% to 5%. [4][5][6][7] Medical management with antibiotics alone or combined with percutaneous aneurysm sac drainage has been offered with various degrees of success. 8,9 However, definitive treatment is complete stent graft explanation with extra-anatomic or in-line reconstruction using a homograft, autogenous veins, or antibiotic-soaked prosthetic grafts. 5 The choice of treatment offered is often dictated by a number of factors, including the patient's overall fitness for surgery. Stent graft explantation has a reported early mortality of #25% and high complication rates. 10,11 Although currently unknown, it is safe to speculate that these risks are higher for patients undergoing fenestrated stent graft (fenestrated endovascular aortic aneurysm repair [FEVAR]) explantation. We present the case of a 74-year-old man with history of FEVAR for a juxtarenal aortic aneurysm. He had presented to an outside institution with constitutional symptoms and found to have an infected stent graft. He underwent partial explantation and reconstruction using a rifampin-soaked Dacron graft with good clinical results and complete resolution of infection found at the 3-and 6-month follow-up examinations and fluorine-18 fluorodeoxyglucose positron emission tomography (PET) scans. The patient provided written informed consent for the report of his case details and imaging studies.

CASE REPORT
A 74-year-old man with cardiovascular risk factors significant for hypertension, hyperlipidemia, chronic obstructive pulmonary disease, congestive heart failure, ongoing tobacco dependence, and 5.6-cm juxtarenal aortic aneurysm underwent three-vessel FEVAR using a Zenith fenestrated stent graft (Cook Medical Inc) with stenting of the superior mesenteric artery and bilateral renal arteries (RAs) in 2015 with good results. He presented to an outside institution 7 years later with complaints of abdominal and back pain, poor appetite, malaise, night sweats, and failure to thrive. The laboratory study results were significant for leukocytosis and hyponatremia. Computed tomography angiography revealed a remodeled aneurysm sac, thickening of the aneurysm wall, and possible periaortic fluid collection that was concerning for aortitis and/or infection (Fig 1, A and B). Broad-  . Similarly, note that the paravisceral aorta is free of any uptake on the preoperative PET scan in the paravisceral aorta (C) but the significant uptake in the infrarenal aorta was limited to the aortic sac, sparing the endograft itself (D-F).  PET revealed increased, noncircumferential, uptake limited to the infrarenal aortic sac tissue suggestive of infection (Fig 1, C-F).
Subsequent computed tomography-guided aspiration of the periaortic fluid returned milky fluid that did not grow any bacteria (Fig 2, A). The patient was offered stent graft explanation but

OPERATIVE DETAILS
The procedure was performed via a midline transperitoneal approach. An attempt was made to perform a left medial visceral rotation. 12 However, severe inflammation was encountered around the visceral arteries and the stent graft appeared well-incorporated in this region, making dissection unsafe. The supraceliac aorta and celiac artery were exposed and prepared for clamping. The patient was systemically heparinized, and the iliac arteries and aorta were clamped at the diaphragmatic hiatus for 10 minutes. The aortic sac was open longitudinally, and all unincorporated tissue was debrided down to the anterior spinal ligament before transferring the clamp to the infrarenal position. The universal bifurcated device was explanted, and the fenestrated cuff was partially excised, leaving a sewing ring in the infrarenal aorta. The periaortic fluid, debrided tissue, and graft were sent to the laboratory for culture. The infrarenal aorta was reconstructed with an 18-mm Â 9-mm rifampin-soaked Dacron graft with a 360 omental wrap (Fig 3). No drains were left in place. The estimated blood loss was 2 L. The patient was discharged home on postoperative day 8 with a 6-week course of ertapenem, followed by amoxicillin and clavulanic acid for 3 months. CTA and PET obtained at 3 and 6 months postoperatively showed no evidence of infection (Fig 4). At the last follow-up, the patient remained asymptomatic and has continued to gain weight.

DISCUSSION
To the best of our knowledge, four cases of FEVAR explantation have been reported in the English literature, making ours the fifth case. Three of these were for infection [13][14][15] and one for a recalcitrant type II endoleak. 16 An additional patient was treated medically using antibiotics, with good results. 17 Unlike our patient, all three patients offered explantation had a secondary aortoenteric fistula (SAEF). In the first patient, the aorta was clamped above the RAs, the bridging stents were crushed and flattened, the entire fenestrated device and bridging stents were removed, and in situ reconstruction was performed in the infrarenal aorta. 15 The second patient underwent complete graft explantation with extensive in situ reconstruction using an autologous vein graft with bypass to the RAs. The procedure was complicated by bowel ischemia requiring resection, and the patient died of multisystem organ failure. 13 The third patient underwent explantation with superior mesenteric artery and bilateral RA reconstruction using a Intergard Synergy antimicrobial graft (Getinge) and did well (Table). 14 For our patient, we had planned for complete stent graft explantation. Our plan changed after realizing that the tissue above the RAs appeared uninvolved in the infectious process. Also, compared with the infrarenal device, the suprarenal stent graft was well incorporated, and no pus, abscess, or any SAEF was found. This was consistent with the PET findings (Figs 1, C-F and 2, B-F). Our decision was guided by reports from the literature showing no reinfection in patients who had undergone partial stent graft explanation, wide infected tissue debridement, in situ reconstruction, and 360 omentum wrapping. 4,18 It is reasonable to argue that an autogenous or a homograft should have been the conduit of choice. The decision to use a rifampin-soaked Dacron graft was because (1) unlike "early" infections, "late" graft infections without obvious SAEF usually result from less virulent pathogens; (2) no pus or abscess was found during the operation; (3) the cultures were negative; and (4) rifampin-soaked Dacron grafts have been proved effective, even in cases of pseudomonas as long as the infected tissue is debrided and the graft is wrapped 360 in omentum, as was it was for our patient (Fig 3). 18 Graft infection recurrence is always a concern and has been reported to occur as early as 2 weeks and as late as 6 years after the initial explantation. 19 As such, close and lifelong follow-up is imperative.

CONCLUSIONS
Partial FEVAR explantation with wide debridement of all infected tissue, followed by in situ reconstruction with a rifampin-soaked Dacron graft and 360 omental wrap, appears to be a safe alternative to complete stent graft explantation for patients with no pus or abscess